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C C Proskauer

Publications and source records attributed to C C Proskauer.

6 recordsLinked to original sources
PubMed1982

Chandelier cells in rat visual cortex.

Golgi-impregnated chandelier cells in rat visual cortex have been examined by both light and electron microscopy. All of the chandelier cells impregnated have their cell bodies within layer II/III and although they occur throughout area 17, there are increased numbers at the area 17/18a border and to a lesser extent at the area 17/18 border. Most of the chandelier cells are bitufted neurons, with groups of dendrites extending from the upper and lower poles of an elongate cell body, but some cells have a more multipolar configuration. The perikaryal cytoplasm is rich in rough endoplasmic reticulum and both the cell body and the sparsely spinous dendrites receive axon terminals forming symmetric and asymmetric synapses. The axons of these neurons arise from either the lower pole of the cell body or the base of one of the dendrites in the lower tuft, and the axons form laterally spread plexuses which terminate in vertical strings of boutons. The boutons in each string synapse with axon initial segments of layer II/III pyramidal cells, the uppermost bouton in each string being 7 to 14 micrometers distant from the pyramidal cell body. Some layer II/III pyramidal cells seem to receive boutons from more than one chandelier cell, others from a single chandelier cell, and still other appear to receive no chandelier cell terminals. The axon terminals of the chandelier cells are irregular in shape, contain pleomorphic synaptic vesicles, and form symmetric synapses. Evidence is presented to show that axon terminals exhibiting the same morphological features and site of synaptic termination as those of the chandelier cells contain glutamic acid decarboxylase (GAD), the enzyme which synthesizes GABA. Hence the chandelier cells are probably GABAergic, inhibitory neurons. Other GAD-positive axon terminals synapse with the cell bodies, axon hillocks, and proximal portions of the axon initial segments of the layer II/III pyramidal cells, and these terminals are probably derived from the smooth and sparsely spinous stellate cells.

Animals↗
PubMed1980

Synaptic relationships between a multipolar stellate cell and a pyramidal neuron in the rat visual cortex. A combined Golgi-electron microscope study.

Two synapsing and impregnated neurons in the rat visual cortex have been examined by a combined Golgi-electron microscope technique in which the Golgi precipitate is replaced by gold particles. One of the neurons is a stellate cell with smooth dendrites and a well impregnated axon, while the other is a layer III pyramidal neuron. Light microscopy showed some boutons from the axonal plexus of the stellate cell closely apposed to the soma and dendrites of the pyramid and it was predicted that synapses were present at these sites. An electron microscopic examination of serial thin sections, in which the profiles of the impregnated neurons are marked by their content of gold particles, showed most of these predicted synapses to exist. Indeed, axon terminals of the stellate cell formed five symmetric synapses with the cell body of the pyramid, one with the apical dendritic shaft and three with basal dendrites. Reasons are given for believing these synapses to be inhibitory. In addition, it was found that one of the axon terminals of the stellate cell synapsed with one of that cell's own dendrites. The significance of this finding is discussed.

Animals↗
PubMed1979

The projection of the lateral geniculate nucleus to area 17 of the rat cerebral cortex. V. Degenerating axon terminals synapsing with Golgi impregnated neurons.

The sites of termination of afferents from the lateral geniculate nucleus to layer IV and lower layer III in area 17 of the rat visual cortex have been determined by use of a combined degeneration--Golgi/EM technique. Degeneration of geniculocortical axon terminals was produced by making lesions in the lateral geniculate body. After the animals had been allowed to survive for two days, the ipsilateral visual cortex was removed and impregnated by the Golgi technique. Suitably impregnated neurons and their processes in layer IV and lower layer III were then gold-toned and deimpregnated for examination in the electron microscope. A search was made for synapses between degenerating axon terminals and the gold-labelled postsynaptic neurons. Geniculocortical synapses were found to involve: (1) the spines of basal dendrites as well as those of proximal shafts and collaterals of apical dendrites of layer III pyramidal neurons; (2) the spines of the apical dendritic shafts and collaterals of layer V pyramidal neurons; (3) the perikaryon and dendritic spines of a sparsely-spined stellate cell; and (4) the perikaryon and dendrites of a smooth, bitufted stellate cell. In view of this variety of postsynaptic elements it is suggested that all parts of the perikarya and dendrites of neurons contained in layer IV and lower layer III which are capable of forming asymmetric synapses can be postsynaptic to the thalamic input. Finally, an analysis of the known neuronal interrelations within the rat visual cortex is presented.

Afferent Pathways↗
PubMed1968

The small pyramidal neuron of the rat cerebral cortex. The axon hillock and initial segment.

The axon of the pyramidal neuron in the cerebral cortex arises either directly from the perikaryon or as a branch from a basal dendrite. When it arises from the perikaryon, an axon hillock is present. The hillock is a region in which there is a transition between the cytological features of the perikaryon and those of the initial segment of the axon. Thus, in the hillock there is a diminution in the number of ribosomes and a beginning of the fasciculation of microtubules that characterize the initial segment. Not all of the microtubules entering the hillock from the perikaryon continue into the initial segment. Distally, the axon hillock ends where the dense undercoating of the plasma membrane of the initial segment commences. Dense material also appears in the extracellular space surrounding the initial segment. The initial segment of the pyramidal cell axon contains a cisternal organelle consisting of stacks of flattened cisternae alternating with plates of dense granular material. These cisternal organelles resemble the spine apparatuses that occur in the dendritic spines of this same neuron. Axo-axonal synapses are formed between the initial segment and surrounding axon terminals. The axon terminals contain clear synaptic vesicles and, at the synaptic junctions, both synaptic complexes and puncta adhaerentia are present.

Animals↗